build_all.bat: improved error handling
build_all.bat: improved error handling

On build errors in Matlab part (building mexopencv or building
AlphaGamma MEX files), display an error dialog, display error
details in Matlab window, and close Matlab only after user
clicked Ok in the error dialog.

rokm/alphagamma-descriptor,rokm/alphagamma-descriptor,rokm/alphagamma-descriptor